Some communications systems utilize packet switched networks that allow packets of information to arrive at a receiver in a different order than they were transmitted. Some applications are sensitive to the received order of packets, and it can be desirable to be able to identify when packets are received out of order so that corrective steps can be taken.
Secure networks are one example of an application sensitive to the received order of packets. In some secure networks, encryption keys used at the transmitter and receiver are synchronized. When encrypted packets are received out of order at the receiver, synchronization can be lost. Another example of an application sensitive to the received order of packets is voice data as voice data processed out of order at a receiver can result in degraded voice quality output.
In order to ensure proper ordering of packets, portions of packets can be dedicated to hold packet-ordering information. For example, a field in a packet header can be used to hold information specifying the relative order of a packet. When the packet contents are read, packets received out of order can be re-arranged into the correct order. However, utilizing portions of a packet to specify relative packet order consumes communications channel bandwidth. It would be desirable for a communications system to be able to specify the order of transmitted packets without consuming communications channel bandwidth.
Accordingly, a significant need exists for a method and apparatus for communicating packet ordering in communications systems without consuming communications channel bandwidth.